The present invention relates to a new and distinct cultivar of Heuchera and given the cultivar name of ‘Red Lightning’. Heuchera is in the family Saxifragaceae. Heuchera ‘Red Lightning’ originated as a controlled cross using Heuchera ‘K265-1’, a proprietary, unpatented, unnamed plant as the seed parent, and Heuchera ‘K259-1’, a proprietary, unpatented, unnamed plant as the pollen parent.
Compared to the seed parent, Heuchera ‘K265-1’, the new cultivar is more vigorous and has a better crown count and darker pattern along the main veins.
Compared to the pollen parent, Heuchera ‘K259-1’, the new cultivar has larger leaves, a darker pattern along the main veins, and no veil.
Compared to Heuchera ‘Delta Dawn’, U.S. Plant Pat. No. 23,545, the new cultivar has larger leaves and habit, and a pattern that stays along the veins, rather than forming a red to dark center.
Compared to Heuchera ‘Electric Lime’, U.S. Plant Pat. No. 21,872, the new cultivar has a habit with more crowns and shorter internodes. The new cultivar has much more prominent red vein coloration.
This new Heuchera is uniquely distinguished by:                1. leaves which are yellow to lime green with prominent red veins, showing the strongest coloration in the spring and fall,        2. large leaves,        3. creamy white flowers on short flowering stems,        4. a medium-large, mounding habit, and        5. good vigor.        
This new cultivar has been reproduced only by asexual propagation (tip cuttings and tissue culture). Each of the progeny exhibits identical characteristics to the original plant. Asexual propagation in 2013 by cuttings and tissue culture using standard micropropagation techniques with terminal and lateral shoots, as done in Canby, Oreg., shows that the foregoing characteristics and distinctions come true to form and are established and transmitted through succeeding propagations. The present invention has not been evaluated under all possible environmental conditions. The phenotype may change with variations in environment without a change in the genotype of the plant.